Six-degree-of-freedom (6DoF) tracking, also known as visual tracking, is a method by which a device (for example, a mixed-reality device, robot, or mobile phone) uses sensors (for example, one or more camera and/or inertial motion unit) to determine its position relative to its surrounding physical environment. For example, a mixed-reality device may use 6DoF tracking to place holograms or digital content in the physical world, and a robot may use 6DoF tracking to navigate itself relative to its surroundings. Of increasing value is the ability a device to operate with a durable and dynamic model of its position relative to the physical environment.
Inside-out tracking is a method by which a device can determine its position without the help of external sensors in the environment. It is often useful for a device that uses inside-out tracking to persist its spatial tracking data over time. However, battery capacity and data storage space of the inside-out tracking device may be limited by physical constraints of the device. When an inside-out tracking device has limited data storage and/or battery life, there is a challenge in storing sufficient information to provide a high-quality user experience.